我想将位图图像的大小减小到最大640px。例如,我的位图图像大小为1200x1200像素...如何将其减小到640px。
我想将位图图像的大小减小到最大640px。例如,我的位图图像大小为1200x1200像素...如何将其减小到640px。
如果您传递位图的宽度
和高度
,则使用以下代码:
public Bitmap getResizedBitmap(Bitmap image, int bitmapWidth, int bitmapHeight) {
return Bitmap.createScaledBitmap(image, bitmapWidth, bitmapHeight, true);
}
如果您想保持位图的比例不变,但将其缩小到最大边长,可以使用:
public Bitmap getResizedBitmap(Bitmap image, int maxSize) {
int width = image.getWidth();
int height = image.getHeight();
float bitmapRatio = (float) width / (float) height;
if (bitmapRatio > 1) {
width = maxSize;
height = (int) (width / bitmapRatio);
} else {
height = maxSize;
width = (int) (height * bitmapRatio);
}
return Bitmap.createScaledBitmap(image, width, height, true);
}
使用此方法
/** getResizedBitmap method is used to Resized the Image according to custom width and height
* @param image
* @param newHeight (new desired height)
* @param newWidth (new desired Width)
* @return image (new resized image)
* */
public static Bitmap getResizedBitmap(Bitmap image, int newHeight, int newWidth) {
int width = image.getWidth();
int height = image.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// create a matrix for the manipulation
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(scaleWidth, scaleHeight);
// recreate the new Bitmap
Bitmap resizedBitmap = Bitmap.createBitmap(image, 0, 0, width, height,
matrix, false);
return resizedBitmap;
}
或者你可以这样做:
Bitmap.createScaledBitmap(Bitmap src, int dstWidth, int dstHeight, boolean filter);
将 filter 参数设为 false 会导致图像出现方块状、像素化。
将 filter 参数设为 true 则能使边缘更加平滑。
以下是可工作的代码,将位图图像分辨率(像素)缩小到所需值...
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;
import android.widget.Toast;
public class ImageProcessActivity extends AppCompatActivity {
private static final String TAG = "ImageProcessActivity";
private static final String IMAGE_PATH = "/sdcard/DCIM/my_image.jpg";
public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
// Calculate the largest inSampleSize value that is a power of 2 and keeps both
// height and width larger than the requested height and width.
while ((halfHeight / inSampleSize) >= reqHeight && (halfWidth / inSampleSize) >= reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
public static Bitmap decodeSampleDrawableFromFile(String file, int reqWidth, int reqHeight) {
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(file, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(file, options);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_process);
new AsyncTask<Object, Object, Bitmap>() {
@Override
protected Bitmap doInBackground(Object... objects) {
try {
return decodeSampleDrawableFromFile(IMAGE_PATH, 640, 640);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
((ImageView) findViewById(R.id.img)).setImageBitmap(bitmap);
}
}.execute();
}
}
获取Bitmap.Options
(图像信息)。
将大小采样到所需的样本大小。
使用给定选项(所需分辨率)从图像文件加载到bitmap
对象中。但是,请在后台线程中执行此操作。
在UI线程上将Bitmap
图像加载到ImageView
中(onPostExecute()
)。